1. Field of the Invention
This invention relates to the area of communication networks. More specifically, the present invention relates to preserving Ethernet frames across a network.
2. Description of the Related Art
Ethernet headers contain useful data. For example, the source address can be used for network analysis, tracing, billing and accounting purposes. Ethernet frames can be tunneled with the Bridge Encapsulation Protocol (BCP) and the Generic Routing Protocol (GRE).
FIG. 1 (Prior Art) is a diagram of transmitting an Ethernet frame with Bridge Control Protocol (BCP) encapsulation. The subscriber's machine 101 (e.g. personal computer (PC)) runs the Internet Protocol (IP) and Ethernet. Data packets are prepared for transmittal to the Internet by prepending IP headers. The subscriber's machine 101 also prepends Ethernet headers onto the data packets to be transmitted. The encapsulation of the data is represented by the protocol stack 103. An encapsulated data packet is transmitted to the customer premise equipment (CPE) 105, such as a cable modem or digital subscriber line (DSL) modem. To preserve the Ethernet frame with BCP, the CPE 105 must run BCP and the Point to Point Protocol (PPP). The CPE 105 encapsulates the data from the subscriber machine 103 with BCP and then PPP. The CPE further prepares the data for transmission by encapsulating the data in delivery protocols (such as 1483 or 1490 bridged circuit over Asynchronous Transmission Mode (ATM), Frame Relay, etc) as indicated by the protocol stack 107. The protocol stack 107 is transmitted to a network element 109. The network element may support BCP and PPP to decapsulate the data packet. The network element 109 is configured as a Layer 2 Tunneling Protocol (L2TP) Access Concentrator (LAC) in order to tunnel the stack or data packet. The LAC 109 encapsulates the data packet with L2TP as indicated by the stack 111 for transmission to an L2TP Network Server (LNS) 113. The LNS 113 must support PPP and BCP to decapsulate the data packet.
FIG. 2 (Prior Art) is a diagram of transmitting traffic from multiple subscribers who use different protocols with multiple Generic Routing Encapsulation (GRE) tunnels. Two individual subscribers 201, 202 connect to two separate CPEs 213, 206. The traffic transmitted from the subscribers 201, 202 to the CPEs 213, 206 are IP encapsulated with Ethernet as indicated by the protocol stacks 205, 204. The CPEs 213, 206 encapsulate the subscriber traffic in a delivery protocol, as indicated by the protocol stacks 209 and 210, and transmit the traffic to a network element 217. Another subscriber 203 transmits traffic to a CPE 215 encapsulated with Point to Point protocol as indicated by the protocol stack 207 showing IP over PPP. The CPE 215 encapsulates the subscriber traffic in a delivery protocol as indicated by the protocol stack 211 and transmits the traffic to a network element 217. The network element 217 uses GRE to tunnel the traffic from subscribers 201, 202, and 203 to another network element 227. The network element 217 establishes 2 different tunnels 223, 225 with the network element 227. One tunnel 223 carries both subscribers' Ethernet traffic. The Ethernet traffic is indicated by the protocol stack 221. The other tunnel 225 carries the PPP subscriber traffic indicated by the protocol stack 219. Both GRE tunnels must be transmitted by IP media also indicated by stacks 221 and 219. The network element 227 terminates the tunnels 223, 225 and routes the traffic to the Internet 229.
Although BCP can be employed to transmit an Ethernet frame, it is an inefficient method. Both PPP and BCP must be supported on the network elements processing BCP data packets. In addition to the network elements, the CPE must also support BCP which is atypical. Moreover, BCP support is in addition to whatever tunneling protocol is to be used. Utilizing GRE to transmit Ethernet frames presents a more efficient and simple method than BCP, but GRE does not have the robust signaling integral to L2TP. Customers requesting certain information passed as attribute values pairs (AVPs) in L2TP lose the option of receiving such information with GRE.